OpenWrt/LEDE Project

  • Status Unconfirmed
  • Percent Complete
  • Task Type Bug Report
  • Category Kernel
  • Assigned To No-one
  • Operating System All
  • Severity High
  • Priority Low
  • Reported Version Trunk
  • Due in Version Undecided
  • Due Date Undecided
  • Private
Attached to Project: OpenWrt/LEDE Project
Opened by Roy Keene - 08.05.2020
Last edited by Adrian Schmutzler - 08.05.2020

FS#3073 - AR8337/AR8327 Flow Control Enabled on Archer C7 v5 (and probably others)

I have a TP-Link Archer C7 v5 (ath79/generic) running OpenWrt 19.07.2 r10947-65030d81f3 and periodically one of my hosts sends out a long-running flood (10/sec) of MPCP Pause frames. The AR8337 switch is configured to honor these frames on port 0 (CPU), and other ports, so stops switching frames essentially forever.

There is no way exposed to user to disable flow control.

Flow control should be turned off unless explicitly requested by the user (e.g., they are in a Datacenter/Enterprise environment and/or doing Fibre Channel over Ethernet). This is exactly the opposite of how it currently is with the added benefit that the user cannot change the behavior.

Here’s a tool that will helpfully generate MPCP Pause frames:

You can use this to bring down your network indefinitely. Additionally, since the AR8337 switch consumes these frames you will not be able to see them from the OpenWRT host.

Ansuel commented on 29.09.2021 12:07

The problem will be autofixed when we will switch to qca8k driver where you can configure flow control.


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